This invention relates to fluid motors, and, more particularly, to fluid motors for backhoes or the like. More specifically, it relates to an improved porting system for such a motor.
Prior art of possible relevance includes the following U.S. Pat. Nos. Rockstrom et al 2,489,326, issued Nov. 29, 1949; Ludwig et al 2,798,462, issued July 9, 1957; Van Auwelaer et al 3,120,897, issued Feb. 11, 1964; and Van Auwelear et al 3,174,635, issued Mar. 23, 1965.
Rotary fluid motors are increasingly being used for rotationally positioning or swinging backhoes or the like for the reason that such motors are compact. While such motors are effective and widely used, operational problems occur due to particular characteristics of the design of the motors and their control systems. In typical prior art structures, the working fluid, normally a hydraulic fluid, is introduced into the motor chamber from either the top or the bottom, but not both. The specific location of supply lines to such ports pose the operational difficulties alluded to previously.
Elevated supply lines serve to purge air to relieve air pockets in the system that result in spongy hydraulic action. However, such lines allow foreign particles typically present in the system to settle and accumulate. As a consequence, some abrasive action against motor seals will occur, thereby lessening the useful life of the motor.
Supply lines to lower motor portions frequently fail to properly vent air or other gases from the hydraulic fluid, with the result that spongy, non-positive hydraulic action occurs.